Insulated testing-plug terminal.



M. H. SHOENBERG & F. TALC-OTT.

INSULATED TESTING PLUG TERMINAL.

APFLICATIQN FILED AUG. I3. |517.

Patented vFeb. 5, 1918. @el ffii-21 C] tto: m2 13 'MLTDN H. SHOENBERG, 0F SAN FRANCIS() 0, AND FRANK TALCOTT, F BUELINGAME,

CALIFORNIA, SSIGNORS T0 MJESTIC ELECTREC DEVELOPMENT COMPANY, d. COI-t- POMTEQN 0F CALIFORNIA.

ENSULATED TESTING-PLUG- TERMINAL.

Bpeoieation of Letters Estant. p

Application med ugust 13, 1917.. Serial No. 138,071.

` testing instruments.

United States, residin the contact bar.

Be it known that we, MJLTON H. SHOEN- nnne and FRANK TALco'r'r, citizens of the at San Francisco and Burlingame, in t e counties of San Francisco and San Mateo and Stateof California, respectively, have invented certain new and useful Im rovements in insulated Testing-Plug Terminals, of which the following is a specification.

rlhis inventionrelates to plug terminals which are adapted to be attached to the conducting cords connected to indicating or rlhe main purpose of our invention is to provide a plug terminal which may be safely used in making connections with the contacts'or conductors on a crowdedswitchboard or in a dark basement or in other places where there is danger of having the or metal substance of opposite polarity.

ln the accompanying drawings, Figure 1 is aside elevation and Fig. 2 a longitudinal sectional view of an insulating plug embodying our invention; and Fig. 3 is a diagrammatic view illustrating the manner of end of the plug.

The contact member consists of a metal pin which is preferably Hattened` and pointed at the forward end 3 and provided with a round threaded shank 3EL which passes through the aperture in the rear end of the plug, being locked in Vposition by means of the nuts 4 and 5. The outer portion of the contact member is surrounded by a tubular sheath or sleeve 7 made of hard rubber or other insulating material and which is provided with an inwardly directed an'ge 7a adapted to bear a ainst the shoulder 3 on coiled spring surrounding the stem of the contact member and interposed between the nut 4 and the inner end of the sheath 7 normally presses the latter outwardly so-that it completely covers the contact member 3. The insulating sheath is adapted to slide freely within the recess in the plug and will readily move inywardlynagainst the pressure of the spring 8 when pressure is brought upon the outer end of the sheath, thereby exposing the contact member U The plug may be attached to the cable or conducting cord of an instrument by loosening the nut 5 until the conductor can be inserted thereunder and held in position by tightening the-nut. The manner of using this plug is illustrated in Fig. 3 in which 10 indicates any instrument such as a testing l device or indicator lto which the plug terterminal come in contact with a conductor t minals are connected. lf it is desired to connect the instrument 10 with the conductors l2, 13, to test the voltage or for other purpose, the plugs are pressed against the cor-- ductor wires and this will cause the insulate ing sleeves 7 to move inwardly within the recess in the plug housing until the contact members 3 come into engagement with the conductors. As soon as the plugs are removed the insulating sheaths or sleeves will be instantly moved outwardly by the springs 8 into the position shown in Figs. l and 2 thereby completely inclosing the contact members 3.

The advantages of our Vinsulating plug terminal will be perfectly apparent and will be especially appreciated by electrical engineers and those who are accustomed to testing electrical circuits where there Vis danger or liability oi' coming into contact smaller. aperture which extends to the rear with the metai surfaces oditierent contacts through accident or inadvertence and where numerous contacts are crowded'closely together. lf the contact member in this plug is completely inclosed by insulating medium so'that it is impossible to accidentally bring the contact into engagement before the operator is ready and when the contact is made, the contact point -is surrounded with an insulating sheath outside of the plane contact. llt will be understood that various changes and modicationsmay be made in the constructions within the scope of our invention.

1. A plug terminal, comprising a main body Yportion of insulating material provided with a longitudinal bore enlarged at one end to form a recess, acontact member extending through said bore and projecting at the recess end beyond the body portion and provided at the opposite end with ratentea web. e, rare.I

ve5 l Within said recess and means for attaching a conductor thereto, and an insulating sheath or sleeve slldably mounted Within said recess and surrounding said contact member.

2. A plug terminal, comprising a main body portion of insulating material pro-l vided with a longitudinal bore enlarged at one end to form a recess, a Contact member.

extending through said bore and projecting at the recess endbeyond the body portion and provided at the opposite end with means for attaching a conductor thereto, an insulating sheath or sleeve slidably molfnted surrounding said contact member, and a spring within the recess that its outer Aen tures.

MILTON H. SHOENBERG. FRANK TALCOTT.

the sheath out'wardly'so asset lforth in claim Civ 

